This calculator looks for the highest purchase price that meets three rules at the same time: the two debt service ratios, the qualifying rate and the minimum down payment. It keeps whichever constraint is tightest.
GDS and TDS. The gross debt service ratio (GDS, called ABD in Quebec) compares housing costs with the household’s gross income: mortgage payment, property tax, heating and half of condo fees. The total debt service ratio (TDS, or ATD) adds all other monthly debts. For an insured mortgage, CMHC sets the maximums at 39% and 44%. For an uninsured mortgage, OSFI Guideline B-20 lets each lender set its own; the calculator applies 39% and 44% in every case. It estimates property tax at 1% of the price per year and heating at $150 per month.
The qualifying rate. Ratios are calculated at the greater of the contract rate plus 2 points or 5.25%: a 4% rate qualifies at 6%. The payment the calculator shows is the payment at this qualifying rate, not your actual payment.
The minimum down payment. 5% up to $500,000, 10% on the portion between $500,000 and $1,500,000, 20% from $1,500,000, the price at which mortgage loan insurance is no longer available. Below 20%, the CMHC premium is added to the loan: 4.00%, 3.10% or 2.80% of the amount borrowed, depending on the down payment. A 30-year amortization is insured only for a first-time buyer or a newly built home, with a premium 0.20 points higher; the calculator applies that surcharge when you choose 30 years.
| Household, 25 years | Contract rate | Maximum price | Binding constraint |
|---|---|---|---|
| $100,000 income, $500 debts, $50,000 down | 4% (qualified at 6%) | $450,000 | TDS 43.96% |
| Same household | 5.5% (qualified at 7.5%) | $405,000 | TDS 43.98% |
| $150,000, $800 debts, $150,000 down | 4.5% (qualified at 6.5%) | $737,000 | TDS 43.97% |
| $200,000, no debts, $30,000 down | 4.5% (qualified at 6.5%) | $550,000 | down payment |
Detail of the first case: a $400,000 loan, a 3.10% premium ($12,400), a $412,400 insured loan. At 6%, the payment is $2,638.56; with $375 of property tax and $150 of heating, housing costs reach $3,163.56, or 37.96% of a monthly income of $8,333.33. With the $500 of debts, TDS rises to 43.96%: that is what sets the ceiling. At the actual 4% rate, the payment would be $2,169.31.
To go further: what salary you need to buy in Montreal or Laval and first-time buyer mortgages in Quebec.
Frequently asked questions
What income do I need to buy a $500,000 house in Quebec?
How does the mortgage stress test work?
What is the minimum down payment to buy a home in Canada?
What are the maximum GDS and TDS ratios?
Why is my maximum price limited by my down payment and not my income?
Where these figures come from
The calculators on this site apply the Quebec rules in force: transfer duty brackets by municipality, CMHC insurance premiums based on the down payment, the legal minimum down payment, the GDS and TDS ratios Canadian lenders use, and the stress test rate. The calculation runs entirely in your browser: no amount you enter is sent anywhere or stored.
What a calculator cannot do
The result is an estimate, not a mortgage pre-approval, not a certified appraisal and not tax advice. A lender decides on your full credit file, your proof of income and the nature of the property. Scales and rates change during the year. Check any figure that matters with your lender, your notary or your accountant before committing. The limits of these tools are set out in the terms of use.
